Finding Out About Matter (p.25-34, 36-39)
Everything thats around us in our environment is made of matter. Matter can be broaden into different categories that distinguishes different types of matter from each other. For an example, all substances have a boiling point but at different temperatures. These characteristics can give matter individuality.
Purfying Matter
When different types of matter are put together, they can either form mixtures or solution. So what are mixtures and what are solutions? Mixtures are when two types of matter that mixes together and the mixture is clearly visible such as having sand mixed in water. Solution is when you mix two different types of matter together but you cannot see with the naked eye such as mixing sugar into water. However, the two elements can be separated through the method of distillation. However, some mixtures of matter are more difficult to separate than others and some solutions may be considered as pure substances until an innovative way of distillating them has been discover.
Characteristics of Pure Substances
Ways to determine the charactersitcs of substances include their boiling point, melting point, and freezing point. Through the characteristics, we can tell the difference between on substance and the other. For example, if we boil the solution of salt wate, the temperature gradually rises when the water boils away. On the other hand, if you just boil pure water, you will find that it boils to a point and continue boiling until the water disappears. This means that pure substances have a constant boiling point. Usually, mixtures don't have constant boiling point. However, some mixtures such as water and grain alcohol have a constant boiling point at 78.2 degrees. Melting and freezing points are also charactersitics to be dicussed. Melting point is the point when a specific type of substance melts while freezing point is the point where a specific type of substance freeze due to the low temperature.
Chemical and Physical Changes
There are two types of changes in matter. One is chemical change and the other is physical change. Chemical changes are changes that do not necessarily have to be seen. The change is determine by the release of energy, colour change, and possibly the smell. After a substance undergoes chemical change, it becomes a new substance and usually it cannot change back to its original form. Chemical changes that break down into two or more new substances is called decompostion. Physical change is the change that you can see with the naked eye and no new substance is formed.
Compounds and Elements
Elements are the bases of a specific type of substances. They can combine with another element that is different from themselves to form compounds such as NaCl (salt). A way to separate compounds to form new substances that can be done with electricity is called electrolysis. This method can decompose substances to form new kinds of matter.
Go to: http://www.youtube.com/watch?v=xYFAj50c7xM to learn more.
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